1. Field of the Invention
The present invention relates to a thermal transfer recording apparatus for image recording on a recording medium by transfer of ink from an ink sheet, and a facsimile apparatus utilizing such recording apparatus.
2. Related Background Art
In general the thermal transfer printer utilizes an ink sheet consisting of a substrate film coated with heat-fusible (or heat-sublimable) ink, and effects image recording by selectively heating said ink sheet with a thermal head according to an image signal, thereby transferring thus fused (or sublimed) ink onto a recording sheet. Since said ink sheet is generally so-called one-time ink sheet in which the ink is completely transferred to the recording sheet by a single image recording, it is necessary, after the image recording of a character or a line, to advance the ink sheet corresponding to the recorded length, thereby securely bringing an unused portion of the ink sheet to the next recording position. Consequently the amount of use of the ink sheet increases, and such thermal transfer printers tend to have a higher running cost in comparison with ordinary thermal printers utilizing thermosensitive recording paper.
In order to solve the foregoing problem, there have already been proposed thermal transfer printers in which the recording sheet and the ink sheet are transported with different speeds, as disclosed in the Japanese Laid-open Patents Application No. 57-83471 and No. 58-201686 and in the Japanese Patent Publication No. 62-58917.
Also for use in such thermal transfer printers, there is already known a multi-print ink sheet capable of plural (n) image recordings. In continuous image recording of a length L, such ink sheet allows to reduce the length thereof, transported during or after said image recording, to a value smaller than L (said value being L/n; n&gt;1). The efficiency of use of the ink sheet can therefore be increased to n times of the conventional efficiency, and a reduction in the running cost of the thermal transfer printer can be expected. Such recording method will hereinafter be called the multi printing method.
In the conventional multi printing, however, the value n is determined independently from the temperature of thermal head, or the ambient temperature and humidity of the location where the apparatus is installed. In thermal transfer printers, a higher temperature of the thermal head or inside the thermal transfer printer facilitates the fusing of ink of the ink sheet, thereby facilitating the recording operation. Consequently the recording operation can be conducted with a larger value of n, namely with a smaller ratio of the amount of transportation of the ink sheet to that of the recording sheet.
On the other hand, a lower temperature of the thermal head or inside the printer hinders the fusion of ink of the ink sheet, thus rendering the recording operation more difficult. Consequently, the recording operation has to be conducted with a smaller value of n, namely with a larger ratio of the amount of transportation of the ink sheet to that of the recording sheet. However the value n in the conventional printers has been selected independently from the temperature, so that the ink sheet has not been utilized efficiently.